Plausible interstellar spacecraft

[3blake7]

I've learned a lot since I started this thread. I made a spreadsheet for each propulsion system.

 

https://docs.google.com/spreadsheets/d/12VQXeNwbLyUAzzwgPj4Qman6c0pUwHcGeE51MLeg5fw/edit?usp=sharing

 

Beamed Core Anti-Matter Rockets aka Pion Rockets has three huge problems. First problem is Anti-Matter Storage Density. The only way to prevent it from colliding with the matter walls and annihilating, is to contain it using a magnetic field, or more specifically a Penning Trap. If you put more Anti-Matter into the storage container, the anti-matter particles will repel each other and expand, increasing the chance of anti-matter particles colliding with the matter wall and annihilating. If you can't store anti-matter at a high enough of a density, then the collective mass of all the storage containers negates the benefits of the pion rocket's very high exhaust velocity. There is another possibility, which is to combine anti-protons with positrons and create anti-hydrogen then freeze the anti-hydrogen into a snowball, which is diamagnetic, and levitate it. However, this has never been done before. There is also the Anti-Matter Production efficiency problem. There are a few scientists, such as Dr. Forward, that believe a 0.01% electricity to anti-proton conversion efficiency is possible with purpose built current technology. The theoretical maximum is 50%, since the creation of an anti-proton also creates a proton at the same time. If the conversion efficiency can't be increased, you would need a Dyson Swarm of millions of solar powered satellites mass producing anti-protons. The last big problem is waste heat. The neutral pions will decay into gamma rays, with some of them colliding with the nozzle and spacecraft. Even with a wireframe like nozzle, which allows most of the radiation to escape through the spaces between the magnetic coils and structural supports, it is still a huge amount of waste heat that still has to be dealt with. The best radiators, Molybdenum-Lithium Heat Pipes, would have to be massive, so massive that it completely negates the high exhaust velocity of pion rockets.

 

Inertial Confinement Fusion Rockets has two huge problems. The first problem is waste heat, which can be as much as 20% of the energy released from fusing Deuterium and Helium-3. If you use a wireframe like nozzle, a lot of the waste heat can escape without colliding with the magnetic coils and the structural supports. You still have to deal with some of the waste heat, which will collide with the magnetic coils and structural supports. You can spread the waste heat out by increasing the radius of the nozzle. However, that means you would need stronger magnetic coils and to shoot the pellets out at a higher velocity. If you use a rail gun, shooting one pellet per second with a 4 kilometer radius bell, is possible but it requires a bigger power plant and more mass. The biggest problem is actually the power requirements for the lasers that crush the pellet and cause fusion. I am not 100% sure I calculated the laser power requirements correctly. I just read that a 2 mm pellet required about 126 watt-hours per cubic millimeter so I scaled it based on the volume of the pellet. If I did that correctly, then the power requirements are absurd and the power plant mass makes the whole idea of large ICF propelled spacecraft unrealistic.

 

I attached an image of an ICF based interstellar ship.

 

Magnetic Confinement Fusion Rockets. I haven't tried calculating this yet, but you have to deal with 100% of the waste heat.

 

Nuclear Pulse Propulsion. The biggest problem with this approach is that it would require a lot of fissile material and the Solar system only has a finite amount.

 

Laser Propelled Light Sail. This is the approach I am currently exploring. I have a 0.5 x 0.5 km diamane light sail with a 3000 kilogram craft with a 1 kilogram payload. I have an array of large lasers, which shoot the light sail for 30 days, accelerating the craft to 12% the speed of light. It only takes about 30 years to reach the closest star! The problem is slowing it down, since the star you are sending it to doesn't have it's own laser array. I considered crashing it into a moon, but the kinetic energy of a 1 kilogram payload would literally hit the moon so hard, that it could start a fusion reaction. I found an experiment where they were testing bacteria's resistance to extremely high accelerations and jerks. I think my payload of self-replicating nano-machines surviving is probably 0%. I tried slowing it down using a pusher plate and nuclear bombs, but the mass of the nuclear bombs made the trip take a lot longer. What I am currently considering is a series of 5 light sails, a primary and the other light sails would be positioned to bounce the lasers and slow down the primary lightsail + craft + payload. I guess the big question is, whether or not an array of lasers can hit something that far away. Also, as the lasers bounce and slow down the payload, it will increase the speed of the reflectors, so the reflectors would need to be able to change their angle.

 

To colonize, the self-replicating nanomachines will replicate for 12 years, then build space stations, laser based interstellar communications satellites and artificial incubators. Then colonists can have their mind copied using nanomachines, uploaded and send via laser to the new star system. When it arrives, the automated systems will grow them a new body and then install their memories and neural configurations. I read that fiber opitics can do up to 320 channels, with each being about 100 Gbit/s. Then you can have the laser beam spot only have a 200000 km diameter with a bunch of satellites in a large orbit, like Pluto, which are spaced 200000 kilometers apart. You could potentially send billions of people per year. Oh yea, for the memory size of a digitalized mind, I went with 200 Terabytes. It could be harder if you include every particle's 3-dimensional coordinates, but that's over kill. All you really need to know is all the neurons different shapes, receptors, different axons and dendrites. Every neuron is made up of the same molecules, same DNA, etc; so all that is redundant.

 

This is the spreadsheet for interstellar laser based communications:

https://docs.google.com/spreadsheets/d/1D36YxIC95-UDhhcnhiQubeXkO2fd5pTFO8iZh_kbGog/edit?usp=sharing

Edited February 23, 2017 by 3blake7

[harlock]

Today the best thing is a shuttlecock spaceship !!!

In the vacuum it's really the best solution for nuclear fusion

micro-explosions propulsion

[LabRat1]

 

For the particle accelerator thrusters, I have 8 sections, each with 11 rings and I am claiming that it can accelerate Argon up to 99.9999999% the speed of light.

 

Have you considered the Einstein's relativity postulate? I mean if somehow you manage that velocity..then wouldn't time in your spaceship slow down...? If so suppose if you see your destination incoming then it would obviously take you some specific amount of time to like pull some lever to slow down the ship..and dont forget about the signals transmitted by the relays...that would take time to transmit too right? So basically by the time you pull the lever and the signals get transmitted and then millennium falcon or enterprise(whatever thou craves ) stops...wont you overshoot?

[Bender]

Why would you control such a spaceship manually?

[Janus]

Have you considered the Einstein's relativity postulate? I mean if somehow you manage that velocity..then wouldn't time in your spaceship slow down...? If so suppose if you see your destination incoming then it would obviously take you some specific amount of time to like pull some lever to slow down the ship..and dont forget about the signals transmitted by the relays...that would take time to transmit too right? So basically by the time you pull the lever and the signals get transmitted and then millennium falcon or enterprise(whatever thou craves ) stops...wont you overshoot?

For one, the velocity he gives here is for the exhaust velocity, not the ship velocity. For the ship to reach that speed (accelerating at 1g) would take several years ship time and an equal amount of time to slow back down. The ship would also have traveled over 21,000 light years reaching this speed and another 21,000 slowing down. So the only way you would ever reach this speed was if you were traveling to somewhere over 41,000 light years away. You would have calculated ahead of time of when you would need to decelerate, so there would be no need to rely on "seeing" your destination.

 

Having said that, even with the stated exhaust velocity, his ship would not be able to even attain that speed without carrying over 44,0000 times the mass of the ship in reaction mass. (it gets much, much worse when you consider that you also have to carry the reaction mass needed to slow down again.)

[LabRat1]

For one, the velocity he gives here is for the exhaust velocity, not the ship velocity. For the ship to reach that speed (accelerating at 1g) would take several years ship time and an equal amount of time to slow back down. The ship would also have traveled over 21,000 light years reaching this speed and another 21,000 slowing down. So the only way you would ever reach this speed was if you were traveling to somewhere over 41,000 light years away. You would have calculated ahead of time of when you would need to decelerate, so there would be no need to rely on "seeing" your destination.

 

Having said that, even with the stated exhaust velocity, his ship would not be able to even attain that speed without carrying over 44,0000 times the mass of the ship in reaction mass. (it gets much, much worse when you consider that you also have to carry the reaction mass needed to slow down again.)

So space travel seems plausible only through wormholes?

[harlock]

I'd want to add some calculations about kinetic energy.

 

If mass(m)=1kg and speed(v)=100e6 km/h(speed of light/10),

kinetic energy(1/2*m*v^2)= 107E6 kwh !!!

It's incredible.

Hot fusion deuterium+deuterium gives ONLY 20e3 kwh/g

Edited March 24, 2017 by harlock

[EdEarl]

So space travel seems plausible only through wormholes?

Such travel is currently science fiction. However, you don't need wormholes, only patience.

[Moontanman]

Containment of antimatter is a problem but Hoyle, in a very old science fiction novel solved that problem by using antimatter iron, he just kept the " anti iron bars" clamped down with magnets in the vacuum of space. Of course finding or getting antimatter iron is a whole new can of worms...

[Janus]

I'd want to add some calculations about kinetic energy.

 

If mass(m)=1kg and speed(v)=100e6 km/h(speed of light/10),

kinetic energy(1/2*m*v^2)= 107E6 kwh !!!

It's incredible.

Hot fusion deuterium+deuterium gives ONLY 20e3 kwh/g

It's closer to 126e6 kwh. Even at just 10% of c you are going to see an some increase in kinetic energy due to relativistic effects.

[KipIngram]

3blake7, kudos for your effort to make your science fiction "hard." Accurate technology doesn't eliminate the need for a great story, but it's always added a lot of enjoyment to science fiction for me.